TITLE: GCN CIRCULAR NUMBER: 5737 SUBJECT: GRB 061019: dust-scattered X-ray halo detected in Swift/XRT DATE: 06/10/19 21:29:32 GMT FROM: Pat Romano at OAB-Swift P. Romano, C. Guidorzi (Univ Bicocca & INAF-OAB), A. Moretti (INAF-OAB), K. L. Page, (U. Leicester) on behalf of the Swift-XRT team Analysis of the Swift XRT observation of GRB 061019 in Photon Counting (PC) mode has revealed in the first three orbits a diffuse X-ray halo centered around the afterglow location. The halo has the form of a complete ring which increases in radius through the observation and reached the distance of >=100 arcsec during the first ~17ks after the trigger (T0). We can exclude it is due to instrumental effects. During the observation, which started ~2800 seconds after the burst trigger time, the observed halo follows the expected behaviour of a "light-echo" as X-rays are scattered by dust in our Galaxy. GRB 061019 is in the direction (Galactic) l = 181.74, b = 4.26 degrees, in which the density of the interstellar medium is quite high as testified by both the neutral Hydrogen column density nH=4.8E21 cm-2 and the optical extinction E(B-V)=1.144 (A_B=4.939).